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Audit of reducing sugars requesting Chris Stockdale Reducing sugars • A sugar which has an aldehyde group capable of reducing Cu(II) % reducing sugar 0 0.25 0.5 0.75 1 Sugar TLC Xylose Glucose Fructose Galactose Sucrose Maltose Lactose 2 Analysis of reducing sugars requesting • Requests from 30/3/11 to 4/5/11 • 66 faeces requests, 13 urine requests • Sugar TLC performed on 56 of these (47 faeces, 9 urines) Urinary reducing sugars STM BRHC Other hospitals When do reducing substances appear in urine? Cause Reducing substances in urine Diabetes mellitus Glucose Galactosaemia Galactose (glucose) Hereditary fructose intolerance Fructose Essential fructosuria (benign) Fructose Essential pentosuria (benign) L-xylulose Alkaptonuria Homogentisic acid Fanconi syndrome Glucose, galactose Liver dysfunction Galactose, fructose Citrin deficiency Galactose Hereditary tyrosinaemia p-Hydroxyphenylpyruvic acid Drugs Salicylate, levodopa, cephalosporins Galactosaemia Hereditary fructose intolerance Enzyme affected Galactose 1 phosphate uridyl transferase (GALT) Aldolase B Incidence 1/45k 1/20k Symptoms Liver & kidney dysfunction, brain damage, hypoglycaemia Liver & renal tubular dysfunction, hypoglycaemia, avoidance of fructose containing foods Onset Symptoms in first week of life Symptoms upon weaning Diagnosis GALT activity assay RBC galactose-1-phosphate Urine galactose/galactitol DNA analysis Nutritional history DNA analysis Reasons for urine requests Hyperbilirubinaemia/jaundice 6 Hypoglycaemia number of requests 5 4 3 2 1 Renal tubular acidosis 0 Reducing substances testing recommended by Metbionet and/or local guidelines for investigation of: • hypoglycaemia • conjugated hyperbilirubinaemia • early presenting jaundice • prolonged jaundice Reducing sugars testing in galactosaemia and HFI ‘although determination of reducing substances in the urine can be used as a first simple screening test for classical galactosaemia, this test should not be used either to confirm or to reject a diagnosis’ • False positive results – Other causes of liver dysfunction • False negative results – Galactosaemia – HFI recent blood transfusion not on regular milk feed literature reports of false negative results Action points: urine • Test no longer available • Clinicians directed to GALT testing when galactosaemia suspected • References to test withdrawn from local guideline documents Faecal reducing substances Faecal reducing substances STM Derriford BRHC Other hospitals GP Taunton Weston Cheltenham Bath Faecal reducing substances Why? • If sugar malabsorption is suspected • Inability to absorb a sugar will lead to its appearance in faeces Lactose malabsorption • • • • • Clinically the most important form of sugar malabsorption Lactase deficiency Lactose accumulation in small intestine Leads to bloating, pain, flatulence, diarrhoea, FTT, colic Primary, secondary and developmental forms Lactose malabsorption • • • • • Clinically the most important form of sugar malabsorption Lactase deficiency Lactose accumulation in small intestine Leads to bloating, pain, flatulence, diarrhoea, FTT, colic Primary, secondary and developmental forms 35 number of requests 30 25 20 15 10 5 0 Diarrhoea/loose stool ?Lactose intolerant FTT Colic Reducing substances testing in diagnosis of lactose intolerance ‘fecal reducing sugars can also be measured and become positive by excretion of a reducing sugar in the stools’ • False negative results – Bacterial metabolism of faecal sugars (can be reduced by freezing samples) • No significant difference could be established between normal children and children with malabsorption syndromes in terms of faecal pH and sugar chromatography. Schaub & Lentze (1973) Sugars, lactic acid and pH in feces of children. A useful diagnostical approach for gastrointestinal disorders? Eur J Pediatrics, 115, 141-53. Alternative tests for diagnosis of lactose intolerance • Hydrogen breath test • Trial of lactose free diet Action points: faeces • Test only available in children up to 16 • Requestors alerted to possibility of false negative results • Advise freezing of samples from external locations • Test no longer performed on fully formed stools • Sugar TLC performed only on samples with 0.5% or above reducing substances Results of the changes to the availability of these tests • Reducing substances testing decreased from 79 to 43 Reason Number of samples excluded Urine 13 Faecal requests on patients >16 4 Fully formed samples 20 Total 37 • Sugar TLC testing decreased from 56 to 12 Reason Number of samples excluded Urine 9 Faecal requests on patients >16 4 Fully formed samples 11 0.25% reducing substances 20 Total 44 Acknowledgements • Clinical Biochemistry, BRI – Ann Bowron – Dr Vicki Powers – Dr Janet Stone • Bristol Royal Hospital for Children – Dr Christine Spray • Metabolic Biochemistry Network – http://www.metbio.net/